Micrometer



July v8, 1925.- i

P. A. BoLTlN MICROMETERl Filed oct. e. i94

3 `-I-wi fication.

Patented July 28, 1925.

UNITED STATES PATENT OFFICE..

PAUL A. PoLTIN, or sT. PAUL, MINNEsoTA.

MIGROMETB.

Application ala october. e, 1924. seria1-^1r. 74r,sa4.

is to produce a micrometer of such novel and improved constructionl that it will m'easure very accurately even if made on a small scale as compared to micrometers heretofore used. This and other objects I attain by the construction and arrangement of parts .illustrated in the accompanying drawing, in which,- Fig. 1 is a side micrometer.V

Fig. 2 isa left hand end view of Fig. 1.

view 'of my improved Fig. 3 is a section on the line'3-3 in4 Fig. 2.

Fig. 4 is a section on Vthe -line .4--4'in F. ig. 1. r l

' Fig. 5 is an enlarged detail view of one of the 'slides 28 in Fig. 3.

v Fig. 6 is aface view of the lower end off the hollow slide member 28 in Fig. 5., thel lower member or lug 28 being removed.

Fig. 7 is the slide member 28* in. Fig. 5

butgiven a longer head.

ZFig. 8 is the same as Fig. 7 but with astill longer head. 1

Fig. 9 isa right hand side view of the locking ring 18 in Figs. 1 and 3.

Fig.'10 is asection on the line 10-10 in Fig. 3, showing the surface ofthe frame lfacing the V'surface or parts shown in Fig.- 9.

Fig. 11 is a face view of fa caliber measuring ring bywhich to set the micrometer. Fig. 12 isian edge vita/w of Fig. 11.

Referring to the drawing by reference numerals, -14 desi ates the -frame of the device. Itl has-a on'tudinal centralibore cavity"`23 in the frame (Fig, V10) and prevent rotation of'the ring. Said ring has its outer; face formed with a cavity 24 having a slanting bottom 25 for a roller 26 to roll on and wedge the ring` 19 together with the contacting ring 18 when the latter is revolved toward the shallow end `of the cavity.

In the head end of the frame are two slides 28, and forward .of said bores are smaller radial bores 29 which are connected with the larger bores by slots 30.. Each slide 28.* has an arm 31 extending through the slot 30 into the smaller bore vwhere it is e5 7 radially aligned bores 27 forV opposite radial constantly pressed toward the bore. 15 vby a coil spring 32 which is supported by an angular end portion 33 of a plate 34 secured by screws 35l and covering the end of `the' bore 15; and hence the springs tend at all times to push the slides 28 'toward each other.

The inner ends of the slides are beveled vat 36'from their centers toward the .-cne

shaped end 37' of the spindle 16." The angle of said bevels and-conesisfifty-three egrees, seven minutes and forty-eight sec-l ends.v This angle of the cone' and forty threads to the inch on the threaded portion 38V of the spindle, and a circular 4scale 39 oftwenty-'ive equaldivisions ulon the variation betweenthe outer@ ends of the.

beveled end of the thimble' 40 com ine to' secure a one-thousandth part of an' inch slides 28 .for each one of the twenty-five degrees' of the. scale 39 that passes the straight line 41 of.scale 42 on a sleeve'43 which is rotatable on'a reduced portion 14a ledcollar45 the .turning of en it about lthe threaded portion' 38 of the 15 for a spindle'16 to slide in andi'a trans'- versely`arranged a erture 17 housing a locking collar 18, byt eturning of which the spindle may be held firmly in any vdesired position, as will be understood from Figs. 9

sand 1() whichyiews show7 that Within the collar 18 is a smaller collar 19 yhaving a reduced portion 20 and a radialgap 21 al- `lowing 1t to bel s rung together tightly about the spindle. gaid inner col1ar\19 also has a radial rib 22 arranged to engage in a' of the frame and is'v held frictionally by a spring 44. Said fraine portion has its rear end 14b reducedV in diameter,t apered out-4 side andthreaded inside and utside, and` is slitted lon 'tudinally and .en a thread- A g1 which will tightspindle suicie screw. The rear end ofthe spindle has a truncated cone-shaped head 46 fitting 1na conical bore 47 1n the rear'end ofthe thimble 38:.A Intolsaid rear-end' o f the spindle is threaded a screw 47 whose head 48 has a` stud with agythumb piece '50 -rotatably V mounted on it and given 'a yieldable ratchet mechanism 51 (whlch being well'lmown'is not here fully described). '521s `awasller helping to Aform connection between the screw-head 48, thimble 40 and spindle cone 46.

The device is so constructed that itmay readily be made for smaller measuresvt-han has been possible witha micrometers heretoreceive any dust found on the adjoining face 55 of the head 56 of the member 28, as 'the latter is rotated some after being inserted.- In Fig. 7 the .member 28 has a head 56 twice as long as the head 56 in Fig. 5, and in Fig.- 8 the head 56b is three times as long as head 56. Each additional length 2J of the head is amultiple of the original head. 'For a medium size tool each additional extensionmay be a -fourth of an inch long. This enables a small micrometer to measure also dimensions greater than the original tool is built for.

`igs. 11 `and 12- show a hardened 'steel ring 57 having its inner face. ground to an exact diameter. of say either one or two inches. In the use of the tool if it is aumed lthe minimum distance between the outer ends of the slides 28 to be about two` inches, then the master gage or caliber ring 57 should be of exactly two inches inside diam- 40 eter. The slides 28 are thenv adjusted by turningv head 48 until the slides contact with the opposite points in the ring 57 and the mark at O on the thimble is turned into convenient view and the sleeve 43 turned with' its. line 41 into registering position with the -mark'0. This done the micrometer is ready to be used by turning of the thimble 40 with the fingers if the operator is 'a mechanic with good judgmentas to the 50 force he applies without injuring the 4instrument. should turn thethimble by the head 50 so that when the slides 28 reach the surface in the hole measured the spring-pressed ratchet If not of such judgm L 51 will yield and let head 50 turn without turning the thimble 40 and spindle 16. In the case ofboring out a hole such as a cylinder, 'in a lathe, the micrometer is set in ent he.

ture.

the manner described to the desired diameter and the cylinder bored to lit over the outer ends of the slides 28. A caliper is then adjusted by the micrometer and used to measure the diameter of the piston that 'is to go into the cylinder. By using the slide members Figs. 7 or 8 one sim ly adds lone fourth,'one-half or three-fourt s of an inch to the capacity of the device andtheref after uses the original parts for ine adjustm'ent of the. increased capacity .as a whole.

What I claim is:

1. In a micrometer the combination of an elongated frame having a central longitudinalvbore. and a head with two o site radial bores in it, a spindle slidable in the` bore and having a portion threaded into a portion. of the bore,-and means at one end for rotating it, the other end being cone shaped at a certain angle, a pair of oppositel movable slides in the radial bores in the ead of the frame and having beveled end portions arranged to be engaged by the opposite faces of the cone and their outer endsl projected beyond the head to form the vmeasuring points and springs ar- .ranged to constantly impel' the slides toward the face of the cone and thus regu-- late the distance between the measurlng points; said head of the frame having also smaller radial bores parallel to the slides and a 'slot connecting the small bore with the large one andv each slide having a lateral arm extending through the slot into the small bore, and said springs being compression coil springs one in each of the small bores-and pressing on the armI to impel the slide toward the cone, and means to retain the outer ends of the springs.

2. The structurespecified in claim l, saidhead of the frame having also smaller radial bores parallel to the slides and a slot connecting the small bore with the large one and each slide having a lateral arm extending through Ithe slot into the small bore, and said springs beingl compression coil springs one in each of the small bores and pressingon the arm; to impel .the slide toward the cone, and means to resist the outer ends of the springs, said head having a closure secured over the end of the bore for the spindle and said closure having angular end portions lforming the retaining means for the outer ends of` the springs.

In testimony whereof I aiiix my signa-- PAUL A. PoLTIHN.

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